This invention relates to grain turner for a grain dryer or the like, and more particularly to such a grain turner which turns the grain from the inside to the outside and vice versa of a vertical grain path as the column moves downwardly within the dryer in such manner that dried grain is substantially dried in all regions of the grain path.
Tower grain dryers are well known. Generally, they comprise a vertical tower of cylindrical or other shape. The tower has a plenum located within the tower. The outer wall of the plenum is perforated and is generally a vertical cylindrical wall. This outer plenum wall has another cylindrical wall spaced outwardly therefrom a distance of about 12 inches (30.48 cm.) so as to form a vertical grain path between the two walls with the cross section of the grain path being an annulus approximately 12 inches thick. As noted, the walls of the grain path are of porous construction such that heated air from within the plenum may be forced through the walls and through the grain in the grain path. Grain to be dried is conveyed to the upper reaches of the tower and fills the space between the outer dryer wall and the plenum so as to form a drying path for the grain to be dried. As dried grain is continuously discharged from the lower end of the grain drying path, additional grain to be dried is loaded into the upper end of the drying path.
The plenum is supplied with heated air by means of one or more burner/blower assemblies. The heated air is forced from within the plenum through the porous or perforated walls of the plenum, through the grain in the drying path, and is forced through the porous outer wall of the tower carrying away moisture from the grain.
Reference may be made to the following U.S. Patents which describe tower or other similar types of grain dryers of the type discussed above: U.S. Pat. Nos. 746,410, 3,333,348, 3,710,449, 3,766,664, 3,864,845, 3,896,562, 3,955,288, 4,004,351, 4,398,356, 4,423,557, 4,914,834, 5,129,164, 5,136,791, 5,556,470, AND 5,651,193.
Conventionally, many of the tower grain dryers and continuous flow portable dryers now used commercially are so-called cross flow column dryers. That is, as the vertical, annular column of grain is metered downwardly, heated air is force outwardly from the plenum through the grain path. Thus, the grain proximate the inner wall of the grain path oftentimes becomes over dried and the grain on the exterior of the grain path is under dried. In order to overcome this uneven drying problem, such tower dryers are often provided with a variety of grain turning device which were intended to reduce the moisture gradient in the grain path by mixing the grain within the grain path once or twice as the grain moves downwardly within the column.
One type of prior art grain turner is known as a grain exchanger. Such grain exchangers splits the grain path in half and channels the grain on the inner reaches of the grain path to the outside of the grain path and channels the grain on the inner portion of the grain path toward the outside of the grain path. One such prior art grain exchanger manufacture by the assignee of the present invention is shown in FIGS. 2 and 3, and is more particularly described hereinafter.
Even though these prior art grain exchangers did succeed in reducing the moisture gradient of the grain path, it was found that instead of moving the grain on the inside of the grain path which received the maximum heating is only channeled part way toward the exterior of the grain path and the grain proximate the outside of the grain path is not fully moved to the inner wall. Thus, such prior art grain turners were not as efficient in turning the grain was would have been desired. Further with such prior art grain turners, were known to waste a considerable amount of energy in drying the grain because of the inefficient mixing of the grain from different regions of the grain paths. Specifically, with the warmest grain on the innermost regions of the grain path nearest the plenum, air movement of the heated air from the plenum took heat from the warmest grain and forced it from the grain path and exhausted it to the atmosphere.
There has been a need for a grain turner which more efficiently turns the grain and, more specifically, which moves the grain widthwise within the grain path as it is turned from the inside to the outside and vice a versa.